This invention relates generally to off-road motor vehicles, such as tractors, and more particularly, to a transmission having shift fork assemblies engageable with slidable shift collars associated with synchronizers to effect a shifting from one gear to another.
Tractor transmissions typically utilize at least two gear shifting assemblies to provide several ranges of gear selections and a plurality of individual gear selections within each range. The shifting of gears to make a selection of ranges or gears within the selected range normally involve the sliding movement of a shift fork on a shift rail to effect the corresponding sliding movement of a shift collar.
The mounting of the shift fork assembly within the transmission requires a positional adjustment of the shift fork relative to the corresponding gear or synchronizer so that proper positional relationships therebetween can be attained and maintained. The servicing of shift fork assemblies is also a concern as shift forks require disassembly and replacement on a periodic basis. The losing of small parts, such as are found in the detents used for holding the shift forks in a selected position, within the transmission is completely unacceptable as such parts can find their way between intermeshing gears to damage expensive transmission components.
Control systems for tractor transmissions require that the transmission be in neutral before the engine can be started. Since the selection of gears, and therefore the speed of operation of the output of the transmission, is accomplished through the manipulation of two or more shift forks, position sensors are operatively coupled to the shift forks to identify when the respective shift fork is in its neutral position. A common practice is to locate the position sensors on the shift rail internally of the transmission housing. This type of design does not monitor the actual location of the shift fork. For example, a loose or mis-adjusted shift fork/shift rail assembly could result in a false shift status signal.
Accordingly, it would be desirable to provide a shift fork position sensor that would be cooperable directly with the shift fork to signal its status in the neutral position.